1. Field of the Invention
This application relates to surgical devices. More particularly, it relates to a method and apparatus for folding and injecting deformable devices, such as an artificial lens into an eye.
2. Background of the Invention
For various reasons, such as cataract or injury, the natural lens of an eye may need replacement or the refractive state of the eye changed by injecting optical devices into the eye. Synthetic lenses for replacement or refractive error modification are available from various manufacturers, who make the lens to the required optical characteristics. For example, intraocular lenses (“IOL”) are often used in treating cataract patients. Implantable contact lenses (“ICL”) may be used to treat myopia (nearsightedness), myopia with astigmatism, hyperopia, and hyperopia with astigmatism.
If the implanted lens or other device is rigid, a relatively large incision is required to accommodate the lens. The use of a flexible lens or other device allows the lens or other device to be rolled or folded and inserted through a smaller incision. The flexible lens or other device is folded, inserted into the eye, and allowed to unfold in position in the patient's eye.
If the flexible lens or other device is implanted with an injector, as opposed to the use of an instrument such as forceps, the size of the incision may be further reduced. A small incision is made in the cornea or sclera through which a small tube, part of the injector, is inserted. The rolled or folded lens or other device is pushed through the injector tube and opens inside the eye.
FIG. 1 shows the basic structure of an eye. Eye 20 has natural lens 10, which is partially exposed at pupil 12 underneath cornea 14. Around pupil 12 is iris 16. Lens 10 is attached to ciliary body 18 within sclera 22. Other tissue, such as choroid 24, retina 26, and fovea 28 are also present. Finally, optic nerve 30 carries optical signals from eye 20 to the brain.
For various reasons, such as cataract or injury, the natural lens of an eye may need replacement. Synthetic lenses for replacement are available from various manufacturers, who make the lens to the required optical characteristics. For cataract surgery, a small incision is made at the junction of cornea 14 and sclera 22. Once the cataract has been pulverized and removed, a soft, folded IOL is inserted through the incision and placed into the lens capsule 10. For ICL or other device implantation, a small incision is made in cornea 14 or sclera 22 and the lens is inserted behind iris 16 through pupil 12 in front of natural lens 10. With a flexible lens and a lens injector, these incisions may be less than 3 mm long and close without use of sutures.
One example of an injector is found in U.S. Pat. No. 6,283,975 B1. The lens is placed in the load chamber of an inserter in an unfolded position. The inserter is then folded which results in the lens also being folded. The load chamber is then placed in an injector and the lens is pushed out of the load chamber into the recipient with a plunger.
Because the lens or other device is not held in place while being pushed out, it may rotate inside the injector and unfold in the wrong orientation (e.g., backwards or inverted). This may also occur if the lens or other device is not properly oriented in the injector before insertion. Rotation may also cause the lens or other device to unfold improperly or incompletely. Improper placement of the lens, which can be difficult to detect, can cause distorted vision or loss of implant effectiveness and increase the likelihood of the recipient developing cataracts or other adverse affects. If any of these problems are detected, the incision must be enlarged so that the lens may be removed and correctly positioned. Thus, there is a need in the art for an injector that can consistently and reliably insert a lens or other device in the proper orientation.